generic: 6.1: add pending patch for ipq4019 MDIO MDC rate fix

generic: 6.1: add pending patch for ipq4019 MDIO MDC rate fix

Add pending patch for ipq4019 MDIO MDC rate fix. The divisor was never
actually set resulting in the MDC rate running at a very low speed.

The same MDIO is used on ipq807x where Aquantia PHY are commonly used
where MDIO is used to load the PHY firmware. Running at higher speed is
required to make the firmware load faster as it does reduce load time
from 60+ second to 5-6 seconds.

Add as pending as upstream there seems to be some conflicts with quic
and me and it might take lots of time before this is effectively merged
upstream.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>